Features of a unique intronless cluster of class I small heat shock protein genes in tandem with box C/D snoRNA genes on chromosome 6 in tomato (Solanum lycopersicum)

Physical clustering of genes has been shown in plants; however, little is known about gene clusters that have different functions, particularly those expressed in the tomato fruit. A class I 17.6 small heat shock protein (Sl17.6 shsp) gene was cloned and used as a probe to screen a tomato (Solanum lycopersicum) genomic library. An 8.3-kb genomic fragment was isolated and its DNA sequence determined. Analysis of the genomic fragment identified intronless open reading frames of three class I shsp genes (Sl17.6, Sl20.0, and Sl20.1), the Sl17.6 gene flanked by Sl20.1 and Sl20.0, with complete 5' and 3' UTRs. Upstream of the Sl20.0 shsp, and within the shsp gene cluster, resides a box C/D snoRNA cluster made of SlsnoR12.1 and SlU24a. Characteristic C and D, and C' and D', boxes are conserved in SlsnoR12.1 and SlU24a while the upstream flanking region of SlsnoR12.1 carries TATA box 1, homol-E and homol-D box-like cis sequences, TM6 promoter, and an uncharacterized tomato EST. Molecular phylogenetic analysis revealed that this particular arrangement of shsps is conserved in tomato genome but is distinct from other species. The intronless genomic sequence is decorated with cis elements previously shown to be responsive to cues from plant hormones, dehydration, cold, heat, and MYC/MYB and WRKY71 transcription factors. Chromosomal mapping localized the tomato genomic sequence on the short arm of chromosome 6 in the introgression line (IL) 6-3. Quantitative polymerase chain reaction analysis of gene cluster members revealed differential expression during ripening of tomato fruit, and relatively different abundances in other plant parts.

Thermal Management of Electronics Using PCM-Based Heat Sink Subjected to Cyclic Heat Load

Designing a heat sink based on a phase change material (PCM) under cyclic loading is a critical issue. For cyclic operation, it is required that the fraction of the PCM melting during the heating cycle should completely resolidify during the cooling period, so that that thermal storage unit can be operated for an unlimited number of cycles. Accordingly, studies are carried out to find the parameters influencing the behavior of a PCM under cyclic loading. A number of parameters are identified in the process, the most important ones being the duty cycle and heat transfer coefficient (h) for cooling. The required h or the required cooling period for complete resolidification for infinite cyclic operation of a conventional PCM-based heat sink is found to be very high and unrealistic with air cooling from the surface. To overcome this problem, the conventional design is modified where h and the area exposed to heat transfer can be independently controlled. With this arrangement, the enhanced area provided for cooling keeps h within realistic limits. Analytical investigation is carried out to evaluate the thermal performance of this modified PCM-based heat sink in comparison to those with conventional designs. Experiments are also performed on both the conventional and the modified PCM-based heat sinks to validate the new findings.

Optimal static voltage stability improvement using a numerically stable SLP algorithm, for real time applications

A numerically stable sequential Primal–Dual LP algorithm for the reactive power optimisation (RPO) is presented in this article. The algorithm minimises the voltage stability index C 2 [1] of all the load buses to improve the system static voltage stability. Real time requirements such as numerical stability, identification of the most effective subset of controllers for curtailing the number of controllers and their movement can be handled effectively by the proposed algorithm. The algorithm has a natural characteristic of selecting the most effective subset of controllers (and hence curtailing insignificant controllers) for improving the objective. Comparison with transmission loss minimisation objective indicates that the most effective subset of controllers and their solution identified by the static voltage stability improvement objective is not the same as that of the transmission loss minimisation objective. The proposed algorithm is suitable for real time application for the improvement of the system static voltage stability.

Selection of Static VAR Compensator Location and Size for System Voltage Stability Improvement

This paper presents a methodology for selection of static VAR compensator location based on static voltage stability analysis of power systems. The analysis presented here uses the L-index of load buses, which includes voltage stability information of a normal load flow and is in the range of 0 (no load of system) to 1 (voltage collapse). An approach has been presented to select a suitable size and location of static VAR compensator in an EHV network for system voltage stability improvement. The proposed approach has been tested under simulated conditions on a few power systems and the results for a sample radial network and a 24-node equivalent EHV power network of a practical system are presented for illustration purposes. © 2000 Published by Elsevier Science S.A. All rights reserved.

An ANN based approach for voltage stability assessment

Artificial Neural Networks (ANNs) have recently been proposed as an alterative method for salving certain traditional problems in power systems where conventional techniques have not achieved the desired speed, accuracy or efficiency. This paper presents application of ANN where the aim is to achieve fast voltage stability margin assessment of power network in an energy control centre (ECC), with reduced number of appropriate inputs. L-index has been used for assessing voltage stability margin. Investigations are carried out on the influence of information encompassed in input vector and target out put vector, on the learning time and test performance of multi layer perceptron (MLP) based ANN model. LP based algorithm for voltage stability improvement, is used for generating meaningful training patterns in the normal operating range of the system. From the generated set of training patterns, appropriate training patterns are selected based on statistical correlation process, sensitivity matrix approach, contingency ranking approach and concentric relaxation method. Simulation results on a 24 bus EHV system, 30 bus modified IEEE system, and a 82 bus Indian power network are presented for illustration purposes.

Voltage stability : some reflections on Q-V characteristics of loads

Considering voltage stability as a static viability problem, this paper takes a particular concern of Q-V characteristics and reflects on certain notions that do not seem to have been explicitly mentioned or derived in the existing documented literature. The equations of Q-V characteristics are rederived in exactness, some salient points on the curve are discovered and analysed. The results of the analysis are illustrated through a case study

Artificial neural network application to power system voltage stability improvement

As power systems grow in their size and interconnections, their complexity increases. Rising costs due to inflation and increased environmental concerns has made transmission, as well as generation systems be operated closer to design limits. Hence power system voltage stability and voltage control are emerging as major problems in the day-to-day operation of stressed power systems. For secure operation and control of power systems under normal and contingency conditions it is essential to provide solutions in real time to the operator in energy control center (ECC). Artificial neural networks (ANN) are emerging as an artificial intelligence tool, which give fast, though approximate, but acceptable solutions in real time as they mostly use the parallel processing technique for computation. The solutions thus obtained can be used as a guide by the operator in ECC for power system control. This paper deals with development of an ANN architecture, which provide solutions for monitoring, and control of voltage stability in the day-to-day operation of power systems.

Novel algorithm for online voltage stability assessment based on feed forward neural network

This paper presents an artificial feed forward neural network (FFNN) approach for the assessment of power system voltage stability. A novel approach based on the input-output relation between real and reactive power, as well as voltage vectors for generators and load buses is used to train the neural net (NN). The input properties of the feed forward network are generated from offline training data with various simulated loading conditions using a conventional voltage stability algorithm based on the L-index. The neural network is trained for the L-index output as the target vector for each of the system loads. Two separate trained NN, corresponding to normal loading and contingency, are investigated on the 367 node practical power system network. The performance of the trained artificial neural network (ANN) is also investigated on the system under various voltage stability assessment conditions. As compared to the computationally intensive benchmark conventional software, near accurate results in the value of L-index and thus the voltage profile were obtained. Proposed algorithm is fast, robust and accurate and can be used online for predicting the L-indices of all the power system buses. The proposed ANN approach is also shown to be effective and computationally feasible in voltage stability assessment as well as potential enhancements within an overall energy management system in order to determining local and global stability indices

Heat shock protein 90 from neglected protozoan parasites

Significant advances have been made in our understanding of heat shock protein 90 (Hsp90) in terms of its structure, biochemical characteristics, post-translational modifications, interactomes, regulation and functions. In addition to yeast as a model several new systems have now been examined including flies, worms, plants as well as mammalian cells. This review discusses themes emerging out of studies reported on Hsp90 from infectious disease causing protozoa. A common theme of sensing and responding to host cell microenvironment emerges out of analysis of Hsp90 in Malaria, Trypanosmiasis as well as Leishmaniasis. In addition to their functional roles, the potential of Hsp90 from these infectious disease causing organisms to serve as drug targets and the current status of this drug development endeavor are discussed. Finally, a unique and the only known example of a split Hsp90 gene from another disease causing protozoan Giardia lamblia and its evolutionary significance are discussed. Clearly studies on Hsp90 from protozoan parasites promise to reveal important new paradigms in Hsp90 biology while exploring its potential as an anti-infective drug target. This article is part of a Special Issue entitled: Heat Shock Protein 90 (HSP90). (C) 2011 Elsevier B.V. All rights reserved.

Evaporation Heat Transfer Coefficient in a Capillary Pumped Loop and Loop Heat Pipe for Different Working Fluids

Capillary pumped loop (CPL) and loop heat pipe (LHP) are passive two-phase heat transport devices. They have been gaining importance as a part of the thermal control system of spacecraft. The evaporation heat transfer coefficient at the tooth-wick interface of an LHP or CPL has a significant impact on the evaporator temperature. It is also the main parameter in sizing of a CPL or LHP. Experimentally determined evaporation heat transfer coefficients from a three-port CPL with tubular axially grooved (TAG) evaporator and a TAG LHP with acetone, R-134A, and ammonia as working fluids are presented in this paper. The influences of working fluid, hydrodynamic blocks in the core, evaporator configuration (LHP or CPL), and adverse elevation (evaporator above condenser) on the heat transfer coefficient are presented.

Plumes Dynamics and Heat Transfer over Horizontal Grooved Surfaces

This study investigates the free convection and plumes dynamics over horizontal surfaces with parallel V-grooves. The convection is studied in a tank of water with the bottom surface being a smooth or grooved surface and the top of the water surface exposed to ambient. Two groove heights were used-10 mm and 3 mm-and the experiment was done with two values of aspect ratio-2.9 and 1.8 (aspect ratio is the width of the fluid layer/height of fluid layer). Heat flux at the bottom surface was from electrical heating. Beyond a certain critical temperature difference, enhanced heat transfer is obtained on the grooved surface compared to a smooth surface. Nusselt numbers are evaluated for both smooth and grooved surfaces and correlated using modified Rayleigh numbers. Visualization shows that the enhanced heat transport in the rough cavities cannot be ascribed to the increase in the contact area; rather, it must be the local dynamics of the thermal boundary layer.

Chemically enhanced thermal stability of anodized nanostructured zirconia membranes

Anodized nanotubular and nanoporous zirconia membranes are of interest for applications involving elevated temperatures in excess of 400 degrees C, such as templates for the synthesis of nanostructures, catalyst supports, fuel cells and sensors. Thermal stability is thus an important attribute. The study described in this paper shows that the as-anodized nanoporous membranes can withstand more adverse temperature-time combinations than nanotubular membranes. Chemical treatment of the nanoporous membranes was found to further enhance their thermal stability. The net result is an enhancement in the limiting temperature from 500 degrees C for nanotubular membranes to 1000 degrees C for the chemically treated nanoporous membranes. The reasons for membrane degradation on thermal exposure and the mechanism responsible for retarding the same are discussed within the framework of the theory of thermal grooving.

Ag-Ni Nanoparticles: Synthesis and Phase Stability

The present study provides an electrodeposition based synthesis method for producing solid solution structured Ag-Ni nanoparticles. It was also observed that the room temperature stable solid solution configuration for the electrodeposited Ag-Ni nanoparticle was a kinetically frozen atomic arrangement and not a thermodynamically stable structure as upon annealing of the Ag-Ni nanoparticles in the ambient atmosphere the solid solution structure decomposed producing phases that were oxides of Ag and Ni. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.esl120008] All rights reserved.